Sensitive cellulosic film and process for producing the same



ED STATES JAQUES EDWIN BRANDENBERGER, 0F PARIS, FRANCE, ASSIGNOR TO LASOGIETE LA CELLOPHANE, OF PARIS, FRANCE.

SENSITIVE CELLULOSIC FILM AND PROCESS FOR PRODUCING THE SAME.

No Drawing.

To all 1.0/1 am it may concern Be it known that I, JA UEs EDWINBRANDENBERGER, citizen of the Republic of Switzerland, and resident ofParis, France, post-office address 16 Rue du Louvre, have invented a newand useful Sensitive Cellulosic Film and Process for Producing the Same,which improvements are fully set forth in the following specification.

This invention relates to photogra'iplhic films which are permeable towater and to a process for the preparation of the same.

Up to the present when photographic films which are permeable to watersuch as cellulose'(viscose) films were being prepared a sensitive salt,for example silver bromide had to be formed by successively treating thefilm in tw baths, for example one containing silver nitrate and theother potassium bromide, the silver bromide sensitive to light beingformed in the interior of the mass. The silver bromide could not be madeto penetrate the interior of the film by means f a silver bromide bath,because this substance is not soluble in water and it is well known thatwater is necessary in the preparation of photographic films frommaterials which are permeable to water.

The operation may be simplified by using a single bath in the followingmanner:

Silver iodide for example,which is a sensitive salt of the same categoryas the bromideis insoluble in water but soluble in an aqueous solutionof potassium iodide.

According to the present invention an aqueous solution of potassiumiodide is prepared in which silver iodide is dissolved until thesolution is saturated.

Thereupon the film is immersed in the bath. As soon as it issufiiciently impregnated it is withdrawn and squeezed and then soaked inwater. The resulting dilution of the potassium iodide solution sets freea large quantity of silver iodide which is deposited in the interior ofthe film and renders the latter sensitive.

The same result can be obtained by using Specification of LettersPatent.

Application filed March 7, 1921.

Patented Jan. si, 1922.

Serial No. 450,400.

for example a warm solution of silver bromide in an alkaline bromide.

What I claim and desire to secure by Letters Patent is:-

l. The process for the production of sensitive cellulosic films forphotographic purposes, which consists in impregnating the film with asolution of a silver halogen salt in a suitable solvent, and thereuponprecipitating the said silver halogen salt within the said film by theaction of a suitable liquid.

2. The process for the production of sensitive cellulosic films forphotographic purposes, which consists in impregnating the film with. asolution of a silver halogen salt in a suitable solvent, and thereuponprecipitating the said silver halogen salt within the said film by theaction of water.

3. The process for the production of sensitive cellulosic films forphotographic purposes, which consists in impregnating the film with asolution of a silver halogen salt in an alkali-halogen salt by heatingit desired. squeezingthe impregnated film and thereupon precipitatingthe said silver halogen salt within the said film by the action ofwater.

4. The process for the production of sensitive cellulosic films forphotographic purposes, which consists in impregnating the film with asolution f silver iodide in potassium iodide, squeezing the impregnatedfilm and thereupon precipitating the said silver iodide within the saidfilm by the action of water.

5. A sensitive cellulosic film for photographic purposes, essentiallycharacterized by the fact that the entire film is impregnated with asensitive salt of silver.

In testimony whereof I have signed this specification in the presence oftwo subscribing witnesses.

JAQUES EDWIN BRANDENBERGER.

Witnesses:

GEORGES PASCAL CARRIERE, GERMAINE MIoHIELs.

